Device for pre-tensioning a machine frame, machine frame, and pressing and drawing device

ABSTRACT

A device for pre-tensioning a machine frame has a tie rod including a first and a further rod head for placement on the machine frame and a tension element for absorbing tensile forces between the rod heads. The tension element extends along a tension distance of the tie rod. At least one of the two rod heads includes a device for reversing the direction for the tension element. In further aspects, a machine frame and a pressing or drawing device are provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e) and the benefit of U.S. Provisional Application No. 61/460,335 filed Dec. 30, 2010 and under 35 U.S.C. §119 of German Application No. 10 2010 055 339.5 filed Dec. 21, 2010, the disclosures of which are incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a device for pre-tensioning a machine frame, having a tie rod comprising a first and a further rod head for placement on the machine frame and comprising a tension element for absorbing tensile forces between the rod heads, whereby the tension element extends along a tension distance of the tie rod.

The invention also relates to a machine frame having an upper crosshead and a lower crosshead for absorbing processing forces introduced into the machine frame, having frame elements for spacing the crossheads apart from one another, and having at least one tie rod that acts between the crossheads, in which the tie rod has a tension element as well as two rod heads, and in which the tie rod is mounted on the crossheads by means of the rod heads.

Furthermore, the invention relates to a pressing or drawing device having a machine frame and having a device for pre-tensioning the machine frame.

2. The Prior Art

Tensioning devices in machine frames, of the type stated, particularly in pressing or drawing devices, are well known from the state of the art. Frequently, such machine frames are structured in a column-type construction. This means that tie rods of the tensioning devices often consist of solid steel columns that are able to absorb both tensile forces and pressure forces. The design, which is heavy in terms of weight, and particularly makes installation of such machine frames difficult, is also a disadvantage. This particularly holds true if solid steel columns are used as tie rods. Furthermore, the dimensions, particularly the length, of such a steel column are also an impediment, since pressing devices, in particular, are often presses having a height of several meters.

Pressing devices in which, on the one hand, tensioning rods only subject to tensile stress and, on the other hand, spacers resistant to pressure are disposed between an upper crosshead and a lower crosshead, are sufficiently known and disclosed, for example, in JP 2001-058238 A.

For example, a press frame or a similar machine frame exposed to great, alternating tensile stresses is described in the published, unexamined patent application DE 22 39 147 A1 and the utility model document JP 54-150181 U, in which frame tensioning elements only subject to tensile stress are disposed between a crosshead and a lower crossbar, on the one hand, and on the other hand, spacer pieces resistant to pressure and firm in shape are provided. The tensioning elements, which consist of high-strength steel wires, reliably absorb the greatest press pressures, to the degree intended, despite their low cross-section. For this purpose, in DE 22 39 147 A1, each tensioning element has a plurality of high-strength steel wires that run essentially parallel to one another, which wires are braced on the crosshead and the lower crossbar by way of tensioning nuts, in each instance. JP 54-150181 U discloses a steel wire, in each instance. Thus, each of the high-strength steel wires reaches once from the crosshead to the lower crossbar. The individual high-strength steel wires of the tensioning element can be handled more easily than a tie rod having a solid steel column. In this regard, the disadvantages of press frames using the column-type design can be avoided.

In the case of another press having a press frame in a pre-tensioned construction, which is described in the published, unexamined patent application DE 23 31 318 A1, corresponding tension elements consist of packages of sheet-metal lamellae, whereby the sheet-metal lamellae run once from a cylinder crossbar to a counter-crossbar of the press frame. The individual sheet-metal lamellae are clamped together, in each instance, as a sheet-metal package, at their ends, by means of pressure supports, so that one tension element for the press frame is formed, in each instance. Here again, the individual sheet-metal lamellae are easier to handle, particularly during installation, than a tie rod having a solid steel column. However, the sheet-metal lamellae are still very high in terms of construction, when a press having a height of several meters is involved.

In the further published, unexamined patent application DE 25 32 108 A1, a press frame is described, in which a tie rod consists of a pre-tensioned mantle composed of individual strips or wires. The pre-tensioned mantle is laid around a yoke and around pillars of the press frame, on the outside, and the individual strips or wires are anchored in the press frame in the foot region of the press frame, in each instance, thereby allowing the pre-tensioned mantle to hold the press frame together. In this connection, each of the individual strips or wires runs around the yoke once. In this construction, the pre-tensioned mantle absorbs the processing forces that are in effect in the press, and the other frame components are relieved of stress, as a result.

In the published, unexamined patent application DE 15 75 278 A1, a machine frame composed of pre-stressed concrete is shown. Here, the machine frame consists of a core that stores the tensile forces, and a sheathing construction homogeneously connected with this core, whereby a winding of high-strength steel wire or strip lies between the core and the sheathing construction, producing the tension in the press body. In this connection, the winding holds a lower part and an upper part of the press body together, in that it is pre-tensioned accordingly. By means of the winding, tensile and bending stresses can then be absorbed in the machine frame composed of pre-stressed concrete. It is true that in this construction, it is possible to do without the use of conventional tie rods. However, the machine frame composed of pre-stressed concrete is very heavy in terms of construction, so that it appears unsuitable, particularly for large presses.

From the published, examined patent applications DE 28 18 511 B1 and DE 30 07 975 B1, a further press frame is known, in which an upper crossbar and a lower crossbar are disposed spaced apart from one another with stands. The press frame has a tensioning device having a plurality of individual tensioning elements, which are mounted or anchored on the upper crossbar and on the lower crossbar with suitable anchoring elements, in each instance. At least one of the crossbars has an arc-shaped wrap-around support for the tensioning elements. The tensioning elements can be mono-filament tensioning steels in the form of round steel or strip steel, or tensioning cables composed of them. Each of the tensioning cables is passed from a first anchoring element to a second anchoring element, whereby the tensioning cable, in each instance, is deflected at one of the crossbars. The tensioning cables are tensioned by means of suitable tensioning devices in the region of the anchoring elements, so that the upper crossbar, the lower crossbar, and the stands disposed between them are pre-tensioned to form the press frame, and the tensioning cables can absorb processing forces within the press frame. It is true that it is possible to do without solid steel columns by means of the use and guidance of the tensioning cables. However, installation of the press frame on site is relatively complicated, since the tensioning cables must be passed through the complete press frame. This is quite difficult in the case of large presses having tensioning cables with correspondingly great dimensions.

SUMMARY OF THE INVENTION

It is the task of the present invention to further develop pre-tensioning devices of the type stated, in such a manner that they have a significantly simpler structure and therefore can be installed more quickly, and nevertheless withstand extremely great stresses.

The task of the invention is accomplished by a device for pre-tensioning a machine frame, having a tie rod comprising a first and a further rod head, for attachment to the machine frame, and comprising a tension element for absorbing tensile forces between the rod heads, whereby the tension element extends along a tension distance of the tie rod, and whereby the device is characterized in that at least one of the two rod heads, preferably both rod heads, comprise(s) a device for reversing the direction for the tension element.

As a result of the device for reversing direction, the rod head or the tie rod as a whole has a particularly simple construction. This is particularly due to the fact that it is possible to do without multiple anchoring and tensioning devices for individual tension elements, as required in the state of the art, since merely a single tension element can be used, which is deflected multiple times.

An advantage to be particularly emphasized can be seen in that when the tie rod or the pre-tensioning device is pre-tensioned, only a single tension element has to be pre-tensioned per tie rod, and therefore the installation effort is significantly simplified. This is particularly advantageous with regard to machine frames having a dimension of a height of several meters. It is understood that if necessary, multiple tension elements can also be provided per tie rod, so that the aforementioned advantage is reduced, but is nevertheless perceptibly present.

Here, the term “tie rod” describes all devices that are used in machine frames to be able to absorb tensile stresses within a machine frame. Such tensile stresses occur within the machine frame as the result of pressing pressures in presses, for example. It is understood that the tie rod can also comprise pressure bars or pressure rods or can be suitable for absorbing pressure forces or other forces, as well. However, in the present case these are not absolutely required, since such pressure devices are ideally made available by a machine frame. In this regard, the structure of the present pre-tensioning device or of the tie rod is further simplified.

In the sense of the present invention, the term “tension element” comprises all devices that can absorb tensile forces, but not any pressure forces, or pressure forces only to a slight degree. For example, a tension element can consist of wires. This already follows from the fact that the device for reversing direction requires corresponding bending of the tension element, whereby all devices that are correspondingly bendable are accordingly unstable with regard to pressure forces or other forces that are not tensile forces.

In advantageous manner, the tension element is configured as a tension cable, particularly as a steel cable. Likewise, the tension element can be a rod, for example a steel rod, or also a strip, for example a narrow strip, for example composed of steel. With regard to good force absorption, particularly with reference to a force/weight ratio, however, cabled structures prove to be particularly advantageous.

The term “tension cable” should be understood to mean essentially an elongated element, consisting of joined wires, which is slack and does not bend, and ideally is elastic, for the transfer of tensile forces. Here, no further details concerning a possible structure of such a tension cable will be discussed, since such tension cables are sufficiently known from the state of the art.

In advantageous manner, the tie rod can be equipped with only a single tension element. In this case, the entire device for pre-tensioning the machine frame is structured in extraordinarily simple manner.

It is understood that in a special embodiment variant, it is also possible that the tie rod comprises more than one tension element.

The device for reversing direction can be designed in many different ways. It can be implemented in structurally particularly simple manner if at least one of the rod heads, preferably both rod heads, has/have a deflection region for the tension element, which region is configured in convex shape. In advantageous manner, the tension element can be deflected on the rod heads multiple times, in particularly gentle manner, as a result, and thus be passed along the tension distance of the tie rod multiple times.

Ideally, the tension element is deflected around a deflection region that is configured in convex shape, which region is situated on the opposite side of the tension distance of the tie rod. In this way, the rod head can be structured and produced in particularly simple manner.

Also, by means of such multiple deflection of merely a single tension element, a particularly great pre-tension of the machine frame can be achieved, with a particularly simple design. Accordingly, the maximal processing forces that can be achieved, for example pressing pressures on a press, can be selected to be accordingly great.

In this regard, the task of the invention is also accomplished by a machine frame having an upper crosshead and a lower crosshead for absorbing processing forces that are introduced into the machine frame, having frame elements for spacing the crossheads apart from one another, and having at least one tie rod that acts between the two crossheads, in which the tie rod has two rod heads at the ends of the tie rod as well as a tension element that acts between the rod heads, and in which the tie rod is mounted on the crossheads by means of the rod heads, in that the tension element is disposed so that it is deflected around at least one of the rod heads.

As has already been described above, with regard to the tensioning device, the entire machine frame also experiences a particularly simple structure, if the tension element is disposed so that it is laid around or turned around at least one of the rod heads.

In this regard, it is specifically possible to do without tensioning and/or anchoring devices on this rod head, so that installation and/or maintenance work with regard to setting a concrete pre-tension of the machine frame is also significantly simplified.

At this point, for the sake of simplicity, it should be pointed out that the machine frame can also be disposed horizontally, so that processing forces such as pressing forces of a press, for example, can act horizontally and not just vertically.

An embodiment variant that should be particularly emphasized provides that the tension element is passed from a first rod head to a further rod head and/or vice versa, multiple times, in such a manner that the ultimate strength of the tie rod is greater than the ultimate strength of the tension element.

For example, the ultimate strength of the tie rod can be twice as great as the ultimate strength of the single tension element, if the tension element is passed between the two rod heads twice, along the tension distance of the tie rod.

If the tension element is passed between the two rod heads a corresponding number of times, along the tension distance, the ultimate strength of the tie rod is increased by a multiple, accordingly, while there is only a single tension element of the tie rod.

In this regard, not only the machine frame but in particular, the pre-tensioning device according to the invention or its tie rod can already be structured in particularly compact manner. Nevertheless, particularly great pre-tension is achieved in this connection, and therefore correspondingly great processing forces are also possible, in advantageous manner.

If the machine frame is furthermore characterized by supports for supporting the rod heads, whereby at least one of the supports comprises a pass-through for the tension element, and whereby the pass-through has a base surface that is greater than a rod head base surface, the installation of the tie rods on the machine frame, in particular, can be significantly simplified, since the rod heads, together with the tension element, can be passed through the support or through the machine frame. In this way, threading work, particularly also in deviation from corresponding solid tension rods, can be significantly simplified.

To attach the tie rod to the support, it is advantageous if the rod head, in each instance, is mounted on the support so that it is oriented crosswise to the longitudinal expanse of the related pass-through. Therefore the rod head merely has to be rotated by about 90° about its vertical axis after it has been passed through the pass-through of the support, and laid down onto the support, in order to be able to install it on the machine frame quickly and easily.

It is understood that rotation of the rod heads can also be superfluous if corresponding support pedestals are put into place between the rod head ends of a rod head and the support, by means of which the pass-through can be bridged. The support pedestals can particularly be used also as tensioning elements or as components of the tensioning device.

It is understood that the embodiment of support and rod head described above is also correspondingly advantageous independent of the other characteristics of the present invention, for a machine frame having an upper crosshead and a lower crosshead for absorbing processing forces introduced into the machine frame, having frame elements for spacing the crossheads apart from one another, and having at least one tie rod that acts between the crossheads, in which the tie rod has two rod heads at the ends of the tie rod, as well as a tension element that acts between the rod heads, and in which the tie rod is mounted on the crossheads by means of the rod heads, in each instance.

The tension element can be pre-tensioned in particularly precise manner within the machine frame, if the support comprises a device for tensioning the tie rod with tensioning elements, in which the tensioning elements are disposed between contact surfaces of the rod head and contact surfaces of the support.

In this connection, the tensioning elements can have many different designs. The tie rod can be easily and reliably pre-tensioned in particularly simple manner if the tensioning elements comprise tensioning wedges.

In this regard, a preferred embodiment variant of the invention also provides that the tensioning device, cumulatively or alternatively, comprises a device for tensioning the tie rod, and the device for tensioning has a wedge-shaped tensioning element, preferably two wedge-shaped tensioning elements. This device for tensioning is especially advantageous if the supports of a machine frame are not equipped with such a device for tensioning the tie rod.

Especially on the basis of the wedge-shaped tensioning elements, pre-tensioning can be undertaken in precise and furthermore extremely simple manner, so that at this point, it should still be noted that such a device for tensioning advantageously further develops known pre-tensioning devices even without the other characteristics.

The machine frame can furthermore be advantageously developed further if it has a device for pre-tensioning the machine frame having one of the characteristics described here.

It is furthermore advantageous if at least one of the rod heads, preferably both rod heads, comprise(s) contact surfaces for a tensioning element of the tie rod on the support side. In this connection, it is advantageous if the contact surfaces are configured to be concave, so that the tensioning elements can interact with the rod heads in particularly reliable manner.

In order to be able to attach the tension element on a rod head in particularly simple manner, in terms of construction, it is furthermore advantageous if one of the two rod heads has a device for accommodating an attachment device of the tension element. Ideally, two attachment devices of the tension element can be attached to the device for accommodation.

Such an attachment device can be, for example, a wedge lock, a cable eye, a forked cable sleeve, or the like, at the ends of the tension element.

It is advantageous if, in this connection, both ends of the tension element are attached on only one of the two rod heads. In this way, installation of the tie rod or maintenance work with regard to the tie rod can be simplified, since corresponding attachment work merely has to be carried out on one of the two rod heads.

In this regard, an advantageous embodiment variant provides that the rod heads of the tie rod are configured asymmetrically.

The structure of the tie rod can be further simplified if the tension element is alternatively configured as an endless tension cable.

In such an embodiment variant, it is possible to do without corresponding attachment devices of the tension element or corresponding devices for accommodating an attachment device of the tension element on the rod heads, since the endless tension cable merely has to be laid around the rod heads, without a special attachment device or the like being required.

If the tension element is disposed so that it is turned around at least one of the two rod heads, tension segments of the tension element can be tensioned along the tension distance on both sides of the rod head, in advantageous manner, in order to be able to absorb tensile forces.

It is particularly advantageous if the tension element is disposed on both sides of at least one of the two rod heads. In this way, the forces can be distributed uniformly over the tensioning elements, for example, in corresponding manner.

Therefore it is advantageous if the tension element has more than one tension segment that acts between the rod heads. In this way, the ultimate strength of the tie rod can be increased to a multiple.

It is furthermore advantageous if the tension element has more than one tension distance section region along the tension distance, so that tensile forces that act on the tension element are distributed over multiple tension segments of the tension element, along the tension distance.

In advantageous manner, the tension element is disposed to be passed from the first rod head to the further rod head and back multiple times, so that multiple tension segments between the rod heads can be in effect with only a single tension element. In this way, the ultimate strength of the tie rod can be increased to a multiple, in particularly simple manner, in terms of construction.

A further advantageous embodiment variant accordingly provides, in this connection, that the tension element is disposed to be passed along the tension distance at least twice, preferably multiple times.

If the tension element has a length that amounts to a multiple of the tension distance, a single tension element can easily be passed along the tension distance multiple times, thereby making it possible to further simplify the structure of the tie rod, as has already been explained.

Further significantly simplified handling of the pre-tensioning device, particularly during the course of installation or transport of the tension element or of the tie rod, exists if the tension element is configured so that it can be rolled up.

It is understood that the tie rod can also comprise more than a single tension element. This is practical, for example, if a single tension element would be too difficult to handle, in view of its size and/or its weight.

A further advantageous embodiment variant provides that the tie rod is adjustable, in variable manner, in terms of its height. For example, different tie rod heights can be set with a single tension element, in that the tension element is passed along the tension distance more or less frequently, as has already been explained multiple times above.

In this way, tie rods of different sizes can be made possible with only a single standard length of a tension element.

In order to be able to also make transport of the present pre-tensioning device simpler, it is advantageous if the tie rod has a working height and at least one further height, such as a transport height and/or an installation height, whereby the further height can amount to less than one third or less than half the working height. Then, a transport height can be easily selected to be very low, for example by rolling it up or consolidating it, thereby causing the advantages of the present arrangement to become clear, particularly also during and before installation.

It is understood that the present device for pre-tensioning a machine frame can be equipped with merely a single tie rod. In most practical cases, the pre-tensioning device comprises at least two tie rods, preferably four tie rods, so that processing forces and tensile forces can be introduced into the existing machine frame symmetrically, and absorbed by the latter.

The task of the invention is accordingly also accomplished, in particular, by a pressing or drawing device having a machine frame and having a device for pre-tensioning the machine frame, whereby the pressing or drawing device is characterized by a pre-tensioning device and/or a machine frame according to one of the characteristics described here.

Further advantages, aims, and properties of the present invention will be explained using the following description of the appended drawing, in which a pre-tensioning device is shown as an example, with one tie rod and with four tie rods for a machine frame of a pressing device.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawing, the figures show:

FIG. 1 schematically, a front view of a press having a conventional press frame, in a stand construction, according to the state of the art;

FIG. 2 schematically, a front view of a tensioning device of a machine frame, having a tie rod comprising a single tension element;

FIG. 3 schematically, a front view of a machine frame of a press, having a tensioning device comprising four tie rods, each having a single tension element; and

FIG. 4 schematically, a top view of a crosshead of the machine frame from FIG. 3, which has supports, each having a pass-through for a rod head of a tie rod.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The press 1 shown in FIG. 1 has a typical structure, known from the state of the art, of a press frame 2, which essentially comprises a cylinder crossbar 3 and a counter-crossbar 4, as well as a stand mechanism 5 composed of four individual pressure supports 6 (numbered only as an example here). A tension rod 7 composed of steel is disposed within each of the pressure supports 6. Each of the tension rods 7 projects beyond the cylinder crossbar 3 and also beyond the counter-crossbar 4 on the outside, so that a tensioning nut 10 or 11 (numbered only as examples here) can be screwed onto the ends 8 and 9, in each instance, of the tension rods 7, in each instance. While the pressure supports 6 space the cylinder crossbar 3 and the counter-crossbar 4 apart from one another, the press frame 2 as a whole is pre-tensioned by means of the tension rods 7. This is done in that the two tensioning nuts 10 and 11 of the tension rod 7, in each instance, are tightened, so that the components cylinder crossbar 3, counter-crossbar 4, and pressure supports 6 are pressed against one another and the press frame 2 is pre-tensioned when this happens. The press frame 2 carries a pressing device 12, which essentially consists of an anvil 13 and a pressing punch 14, including a drive unit 15 having a cylinder that is disposed on the cylinder crossbar 3. The anvil 13, in contrast, is provided on the counter-crossbar 4. During work with the pressing device 12, high pressure forces 16 occur, which must be absorbed by the press frame 2. For this purpose, the tension rods 7 are provided, which counteract the pressure forces 16. In this regard, the tension rods 7 are subject to tensile stress, and must be dimensioned in correspondingly strong manner, so that the pressure forces 16 do not plastically deform the press frame 2. It can easily be imagined that the tension rods 7 must be designed to be very large in the case of large presses having a pressing force of several tons, and therefore they are very heavy in construction and are correspondingly difficult to handle, particularly during installation of the horizontal press 1. Furthermore, pre-tensioning of the tension rods 7 is relatively complicated, since the tensioning nuts 10 and 11 can often be installed only using heavy equipment. In the case of very large presses, like the horizontal press 1 shown here, there is the additional difficulty that the tension rods 7 are difficult to handle because of their great length. These are only some reasons why press frames 2 having conventional tension rods are disadvantageous.

Significant disadvantages of conventional devices are avoided with the pre-tensioning device 20 shown in FIG. 2.

The pre-tensioning device 20 has a tie rod 21 that essentially consists of a first rod head 22, a further rod head 23, and a single tension element 24.

In this connection, the single tension element extends from the first rod head 22 to the further rod head 23, along a tension distance 25, and absorbs tensile forces that act between the rod heads 22 and 23.

In this exemplary embodiment, the two rod heads have a device 26 for reversing direction (numbered only as an example here, with regard to the first rod head 22) for the single tension element 24. As a result, it is possible to have multiple tension segments 27 act between the two rod heads 22 and 23, with only a single tension element 24, so that the ultimate strength of the present tie rods 21 amounts to a multiple of the ultimate strength of the single tension element 24.

In this regard, the single tension element 24 has more than one tension distance section region 28 along the tension distance 25, so that tensile forces that act on the single tension element 24 along the tension distance 25 are distributed over multiple tension segments 27 of the single tension element 24.

The single tension element 24 is therefore disposed so that it is passed from the first rod head 22 to the further rod head 23 and back multiple times. In order to be able to pass the single tension element 24 along the tension distance 25 multiple times, it has a length that amounts to a multiple of the tension distance 25. In this exemplary embodiment, the single tension element 24 consists of a tension cable 29 in the form of a steel cable.

It is understood that in alternative tie rods, other tension elements, different from the tension cable 29 shown here, can also be used.

In this regard, the single tension element 24 in this exemplary embodiment is configured so that it can be rolled up, so that it can easily be consolidated during transport of the present pre-tensioning device 20. Rolled up or consolidated in this manner, a transport volume of the tie rod 21 is advantageously reduced by a multiple.

In this regard, the present tie rod 21 can assume a working height and at least one further height, such as, for example, an installation height and/or a transport height, whereby the further height can amount to less than one-third or less than half of the working height.

In advantageous manner, the entire tie rod 21 can be variably adjusted in its height, since the single tension element 24—depending on the usage requirements—can be deflected at the rod heads 22 or 23 a different number of times.

A deflection at the rod heads 22, 23 is configured in particularly advantageous manner, since the two rod heads 22, 23 have a deflection region 30 for the single tension element 24, which region is configured in convex shape.

If the single tension element 24, as shown here, is not configured as an endless tension cable—which then can simply be laid around the deflection region 30 of the two rod heads 22 or 23, in each instance—it is advantageous if at least one of the two rod heads 22, 23, in this exemplary embodiment the further rod head 23, has a device 31 for accommodating the attachment devices 32 (numbered only as examples here) of the single tension element 24. In advantageous manner, the two ends of the single tension element 24 are thus attached to the further rod head 23, thereby further simplifying the installation of the tie rod 21. In this regard, the two rod heads 22 and 23 in this exemplary embodiment are configured asymmetrically. In this connection, it is understood that in an alternative embodiment, the rod heads can be configured to be symmetrical, thereby reducing the number of different parts, whereby it is nevertheless possible to attach the tension element 24 only to one of the rod heads; likewise, however, it can then also be attached to both rod heads.

In order to be able to pre-tension the pre-tensioning device 20 or the tie rod 21 in suitable manner, the pre-tensioning device 20 has devices 35, 36 for tensioning the tie rod 21, whereby the tensioning device 35, 36 comprises wedge-shaped tensioning elements 37 and 38, in each instance, (numbered only as examples here, with regard to the second tensioning device 36). The wedge-shaped tensioning elements 37, 38 are equipped, in this exemplary embodiment, with contact surfaces 39 configured in convex shape, on the rod head side (see numbering of first tensioning device 35). Accordingly, the two rod heads 22, 23 have contact surfaces 40 (also numbered only as an example here, on the first tensioning device 35) configured in concave shape, which are also part of the tensioning device 35, 36.

Furthermore, the individual wedge-shaped tensioning elements 37, 38 also have flat contact surfaces 41 (numbered only as examples here, with regard to the second tensioning device 36). The rod heads 22, 23 can be laid onto a component of a machine frame 50 (see FIG. 3), which component is suitable for this purpose, by means of the flat contact surfaces 41, by way of the wedge-shaped tensioning elements 37, 38.

The machine frame 50 shown in FIG. 3 has an upper crosshead 51, a lower crosshead 52, and frame elements 53 (numbered only as examples here), for spacing the two crossheads 51 and 52 apart from one another, similar to the known press 1 consisting of press frame 2, cylinder crossbar 3, counter-crossbar 4, and stand mechanism 5.

In this exemplary embodiment, the machine frame 50 carries a pressing device 54, not shown in any detail, whereby, however, in the final analysis, it does not play any role in what manner the tensile forces to be absorbed by the tie rods 21 are applied.

The machine frame 50 has a pre-tensioning device 20 that is equipped, in this exemplary embodiment, with a total of four tie rods 21. The four tie rods 21 are identical, in terms of their structure, with the tie rod 21 described in FIG. 2. In order to avoid repetition, no renewed explanation of the tie rod 21 on the machine frame 50 will be presented. Components or component groups that are the same or have the same effect are also provided with identical reference numbers here.

In this regard, it should only be pointed out that the machine frame 50 experiences a particularly simple structure, since the single tension element 24 is disposed to be passed between the two rod heads 22 and 23, along the tension distance 25, multiple times, on every tie rod 21, in that the single tension element 24 is disposed to be deflected around the two rod heads 22 and 23 multiple times.

In this regard, the ultimate strength of each of the four tie rods 21 is greater than the ultimate strength of the single tension element 24, so that the machine frame 50 can withstand particularly great processing forces.

It can clearly be seen that each of the rod heads 22, 23 is mounted on the crossheads 51, 52 by means of the wedge-shaped tensioning elements 37, 38 (numbered only as examples here), whereby the two crossheads 51 and 52 form supports 55, in each instance, for mounting (numbered only as examples) the rod heads 22, 23.

The structure of such a support 55 can be seen particularly well in the detail view 56 of FIG. 4. In the detail view 56, a region of the upper crosshead 51 of the machine frame 50 from FIG. 3 is shown as an example.

The support 55 has a pass-through 57, through which the first rod head 22 can be inserted from below, since the base surface 58 of the pass-through 57 is selected to be greater than the rod head base surface 59.

In the installed state of the tie rod 21, as it is shown in FIGS. 3 and 4, in each instance, the rod head 22 is disposed crosswise to the longitudinal expanse 60 of the pass-through 57, and thus laid onto the support 55, which is made available by the upper crosshead 51. In advantageous manner, particularly simple installation of an already pre-mounted tie rod 21 on an already set-up machine frame 50 is therefore possible.

By means of the machine frame 50 configured in this manner, a pressing device 54 that has a particularly compact construction is implemented, which is characterized in that it can withstand extremely great stresses, despite a pre-tensioning device 20 that has a particularly simple structure.

REFERENCE SYMBOL LIST

-   1 press -   2 press frame -   3 cylinder crossbar -   4 counter-crossbar -   5 stand mechanism -   6 pressure supports -   7 tension rod -   8 first end of the tension rod -   9 second end of the tension rod -   10 first tensioning nut -   11 second tensioning nut -   12 pressing device -   13 anvil -   14 pressing punch -   15 drive unit -   16 pressing forces -   20 pre-tensioning device -   21 tie rod -   22 first rod head -   23 further rod head -   24 single tension element -   25 tension distance -   26 device for reversing direction -   27 tension segments -   28 tension distance section region -   29 tension cable -   30 deflection region -   31 device for accommodation -   32 attachment devices -   35 first tensioning device -   36 second tensioning device -   37 first wedge-shaped tensioning element -   38 second wedge-shaped tensioning element -   39 convex contact surfaces -   40 concave contact surfaces -   41 flat contact surfaces -   50 machine frame -   51 upper crosshead -   52 lower crosshead -   53 frame elements -   54 pressing device -   55 support -   56 detail view -   57 pass-through -   58 base surface -   59 rod head base surface -   60 longitudinal expanse 

1. Device (20) for pre-tensioning a machine frame (50), having a tie rod (21) comprising a first and a further rod head (22, 23) for placement on the machine frame (50) and comprising a tension element (24) for absorbing tensile forces between the rod heads (22, 23), whereby the tension element (24) extends along a tension distance (25) of the tie rod (21), wherein at least one of the two rod heads (22, 23) comprises a device (26) for reversing the direction for the tension element (24).
 2. Pre-tensioning device (20) according to claim 1, wherein the two rod heads (22, 23) comprise a device (26) for reversing the direction for the tension element (24).
 3. Pre-tensioning device (20) according to claim 1, wherein at least one of the rod heads (22, 23) has a deflection region (30) for the tension element (24), which region is configured in convex shape.
 4. Pre-tensioning device (20) according to claim 3, wherein rod heads (22, 23), have a deflection region (30) for the tension element (24), which region is configured in convex shape.
 5. Pre-tensioning device (20) according to claim 1, wherein both ends of the tie rod (24) are attached to a single one (23) of the two rod heads (22, 23).
 6. Pre-tensioning device (20) according to claim 1, wherein one (23) of the two rod heads (22, 23) has a device (31) for accommodating an attachment device (32) of the tension element (24).
 7. Pre-tensioning device (20) according to claim 1, wherein the rod heads (22, 23) of the tie rod (21) are configured asymmetrically.
 8. Pre-tensioning device (20) according to claim 1, wherein at least one of the rod heads (22, 23), preferably both rod heads (22, 23), comprise(s) contact surfaces (39) for a tensioning element (37, 38) of the tie rod (21), on the support side.
 9. Pre-tensioning device (20) according to claim 8, wherein the contact surfaces (39) are configured in concave shape.
 10. Pre-tensioning device (20) according to claim 1, wherein the tension element (24) is disposed so that it is turned around at least one of the two rod heads (22, 23).
 11. Pre-tensioning device (20) according to claim 1, wherein the tension element (24) is disposed on both sides of at least one of the two rod heads (22, 23).
 12. Pre-tensioning device (20) according to claim 1, wherein the tension element (24) has more than one tension segment (27) that acts between the rod heads (22, 23).
 13. Pre-tensioning device (20) according to claim 1, wherein tension element (24) is disposed so that it is passed from the first rod head (22) to the further rod head (23) and back multiple times.
 14. Pre-tensioning device (20) according to claim 1, wherein the tension element (24) is disposed so that it is passed along the tension distance (25) at least twice, preferably multiple times.
 15. Pre-tensioning device (20) according to claim 1, wherein tension element (24) has a length that amounts to a multiple of the tension distance (25).
 16. Pre-tensioning device (20) according to claim 1, wherein the tension element (24) has more than one tension distance section region (28) along the tension distance (25), so that tensile forces that act on the tension element (24) are distributed over multiple tension segments (27) of the tension element (24).
 17. Pre-tensioning device (20) according to claim 1, wherein the tension element (24) is configured as a tension cable (29), particularly as a steel cable.
 18. Pre-tensioning device (20) according to claim 1, wherein the tension element (24) is configured so that it can be rolled up.
 19. Pre-tensioning device (20) according to claim 1, wherein the tension element (24) is configured as an endless tension cable.
 20. Pre-tensioning device (20) according to claim 1, wherein the tie rod (21) has more than one tension element (24).
 21. Pre-tensioning device (20) according to claim 1, wherein the tie rod (21) is variably adjustable in its height.
 22. Pre-tensioning device (20) according to claim 1, wherein the tie rod (21) has a working height and at least one further height, such as a transport height and/or an installation height, whereby the further height can amount to less than one-third or less than half of the working height.
 23. Pre-tensioning device (20) according to claim 1, wherein the pre-tensioning device (20) comprises at least two tie rods (21), preferably four tie rods (21).
 24. Pre-tensioning device (20) according to claim 1, wherein the pre-tensioning device (20) comprises a device (35, 36) for tensioning the tie rod (21), and the device (35, 36) for tensioning has a wedge-shaped tensioning element (37), preferably two wedge-shaped tensioning elements (37, 38).
 25. Machine frame (50), having an upper crosshead (51) and a lower crosshead (52) for absorbing processing forces introduced into the machine frame (50), having frame elements (53) for spacing the crossheads (51, 52) apart from one another, and having at least one tie rod (21) that acts between the crossheads (51, 52), in which the tie rod (21) has two rod heads (22, 23) at the ends of the tie rod (21), as well as a tension element (24) that acts between the rod heads (22, 23), and in which the tie rod (21) is mounted on the crossheads (51, 52) by means of the rod heads (22, 23), wherein the tension element (24) is disposed between the rod heads (22, 23) of the tie rod (21) multiple times, wherein the tension element (24) is disposed so that it is deflected around at least one of the rod heads (22, 23).
 26. Machine frame (50) according to claim 25, wherein the tension element (24) is passed from a first rod head (22) to a further rod head (23) and/or vice versa multiple times, in such a manner that the ultimate strength of the tie rod (21) is greater than the ultimate strength of the tension element (24).
 27. Machine frame (50), having an upper crosshead (51) and a lower crosshead (52) for absorbing processing forces introduced into the machine frame (50), having frame elements (53) for spacing the crossheads (51, 52) apart from one another, and having at least one tie rod (21) that acts between the crossheads (51, 52), in which the tie rod (21) has two rod heads (22, 23) at the ends of the tie rod (21), as well as a tension element (24) that acts between the rod heads (22, 23), and in which the tie rod (21) is mounted on the crossheads (51, 52) by means of the rod heads (22, 23), comprising supports (55) for mounting at least one of the rod heads (22, 23), whereby at least one of the supports (55) comprises a pass-through (57) for the tension element (24), and whereby the pass-through (57) has a base surface that is greater than the rod head base surface.
 28. Machine frame (50) according to claim 27, wherein the rod head (22, 23), in each instance, is mounted on the support (55) so that it is oriented crosswise to the longitudinal expanse of the related pass-through (57).
 29. Machine frame (50) according to claim 27, wherein the support (55) comprises a device (35) for tensioning the tie rod (21), having tensioning elements (37, 38), in which the tensioning elements (37, 38) are disposed between contact surfaces of the rod head (22, 23) and contact surfaces of the support (55).
 30. Machine frame (50), having an upper crosshead (51) and a lower crosshead (52) for absorbing processing forces introduced into the machine frame (50), having frame elements (53) for spacing the crossheads (51, 52) apart from one another, and having at least one tie rod (21) that acts between the crossheads (51, 52), in which the tie rod (21) has two rod heads (22, 23) at the ends of the tie rod (21), as well as a tension element (24) that acts between the rod heads (22, 23), and in which the tie rod (21) is mounted on the crossheads (51, 52) by means of the rod heads (22, 23), comprising supports (55) for mounting at least one of the rod heads (22, 23), whereby at least one of the supports (55) comprises a pass-through (57) for the tension element (24), and whereby corresponding support pedestals are placed between the rod head ends of the rod head (22, 23) and the support (55), by means of which a pass-through (57) is bridged.
 31. Machine frame (50) according to claim 25, further comprising a device (20) for pre-tensioning the machine frame (50), said device having a tie rod (21) comprising a first and a further rod head (22, 23) for placement on the machine frame (50) and comprising a tension element (24) for absorbing tensile forces between the rod heads (22, 23), whereby the tension element (24) extends along a tension distance (25) of the tie rod (21), wherein at least one of the two rod heads (22, 23) comprises a device (26) for reversing the direction for the tension element (24).
 32. Pressing or drawing device having a machine frame (50) and having a device (20) for pre-tensioning the machine frame (50), wherein the pressing or drawing device comprises a pre-tensioning device (20) and/or a machine frame (50) according to claim
 1. 